If filtration apparatuses are utilized for long periods of time, filtration sand (filtration media) within filtration tanks of the filtration devices becomes clogged due to suspended matter in liquid to be filtered, such as water. This prevents the performance of efficient filtration, and deteriorates the quality of filtered water. For this reason, clogging is eliminated by removing contaminants (suspended matter), which are attached to the filtration media. To this end, it is necessary to exchange the filtration media or to manually remove and cleanse the filtration media from the filtration tank, and to return the cleansed filtration media to the filtration tank after the suspended matter is separated from the filtration media. These operations are highly labor intensive, and also require space to cleanse the removed filtration media. In addition, in the case that the filtration media are to be discarded, a great amount of industrial waste is generated. Therefore there are known filtration apparatus that enable such cleansing operations to be performed automatically and in a space efficient manner.
As an example of a filtration apparatus capable of automatically cleansing filtration media, there is a known filtration apparatus having a cleansing mechanism (cleansing apparatus) for cleansing filtration media within a filtration tank. The cleansing mechanism is caused to operate at predetermined temporal intervals to cleanse the filtration media, and suspended matter which is separated from the filtration media is expelled to the exterior from the filtration tank (Patent Document 1 and Patent Document 2).
However, if a user who is utilizing an existing filtration tank without a built in cleansing apparatus wishes to cleanse filtration sand in a simple manner and with little effort, it would become necessary for the user to purchase a filtration apparatus having a cleansing apparatus as disclosed in Patent Document 1 or Patent Document 2 to replace the user's entire filtration apparatus, which would result in cost increases.
In order to solve this problem, the present applicants have proposed a filtration media cleansing apparatus which is mountable to the exterior of existing filtration apparatuses.
Patent Document 1:
International Publication No. WO01/83076
Patent Document 2:
Japanese Unexamined Patent Publication No. 2004-121885
Patent Document 3:
Japanese Unexamined Patent. Publication No. 2008-284457
Here, the configuration of a filtration media cleansing apparatus 401 which is mountable to the exterior of existing filtration apparatuses will be described with reference to FIG. 15.
The filtration media cleansing apparatus 401 has a metal cylindrical outer cylinder 402, a screw conveyor 404 placed in the interior of the outer cylinder 402, and a drive section 406 coupled to the upper end of the screw conveyor 404. A base 412 having a bearing 414 that axially supports the shaft 416 of the screw conveyor therein is linked to the upper end of the outer cylinder 402. A large diameter portion 434 having an inlet 436, through which filtration media and liquids such as water are introduced, formed therein is linked to the lower end of the outer cylinder 402. An introducing pipe 438 is welded onto the inlet 436. In addition, an outlet 460, through which filtration media are expelled, is formed within a side surface of at the upper end portion of the outer cylinder 402, and an expelling pipe 461 is mounted to the outlet 460. The introducing pipe 438 and the expelling pipe are inserted within a filtration apparatus. Filtration media which are suctioned through the introducing pipe 438 are cleansed within the filtration media cleansing apparatus 401. Thereafter, the cleansed filtration media are expelled into the filtration apparatus through the expelling pipe 461.
In the filtration media cleansing apparatus 401, the screw conveyor 404 is rotated to convey the filtration media suctioned through the inlet 436 upward while scrubbing the filtration media. Thereafter, the cleansed filtration media 460 are expelled through the outlet 460. However, because the upwardly conveying force of the screw conveyor 404 is strong, particles of filtration media enter the bearing 414 through a seal portion 414C of the bearing 414 directly above the screw conveyor. There is a possibility that the filtration media will wear down the bearing 414 and the shaft 416, causing axial shifts to occur and damaging the bearing 414. For this reason, a filtration media cleansing apparatus having improved durability is desired.
The present invention has been developed in view of the foregoing circumstances, and it is an object of the present invention to provide a filtration media cleansing apparatus capable of being externally mounted to an existing filtration apparatus, having improved durability.